Microstructural evolution and thermo-mechanical behaviour of fine-grain graphite materials

像费米实验室的LBNE这样的高能粒子物理实验需要中微子的生产和研究。细颗粒石墨材料被选为中微子产生靶材料，它被高功率、高能、强质子束以短脉冲周期(340kW、120GeV、1.1 mm束流西格玛和微秒脉冲时间)周期性地照射。因此，这些具有复杂的多尺度微观结构(从纳米到宏观)的纳米晶石墨的辐照行为描述了它们作为质子辐照靶和中微子产额的使用寿命和性能。石墨的多尺度微结构控制着它们的微观和整体热机械性能，因此，必须采用多尺度表征和实验力学方法来全面了解目标石墨的质子辐照行为。该项目将主要使用微拉曼光谱、微X射线层析成像(MicroXCT)、聚焦离子束扫描电子显微镜(FIB-SEM)、中子衍射、X射线衍射、小角X射线散射(SAXS)、数字体积/图像相关和各种(微观)机械测试方法(原位和/或非原位)来检测未辐照和未辐照的细粒目标石墨材料以及在核石墨行业中流行的其他几种同类材料。希望通过这个博士项目，能够对这些现代细粒核石墨的代表有一个全面和完善的机械理解，并在各种物理/工程应用中验证它们的可靠性，包括世界各地的下一代裂变反应堆系统(熔盐和高温气冷堆)和加速器驱动的设施。

High energy particle physics experiments such as LBNE at Fermilab require the production and study of neutrinos. Fine-grained graphite materials have been selected as neutrino production target materials that have been constantly irradiated by high power, high energy and intensified proton beams operating cyclically with short pulse period (340KW, 120GeV, 1.1mm beam sigma and microseconds pulse time). Therefore, the irradiation behaviours of these nano crystalline graphite with complex multiple-length scale microstructures (nano to macro) depict their useful lifetime and performance for being proton irradiation target and neutrino yields. The multiple-length scale microstructures of graphite control their micro- and bulk thermo-mechanical properties and as such, a multi-length scale characterisation and experimental mechanics methodology must be adopted for a comprehensive understanding of target graphite's proton irradiation behaviour to be acquired. This project will be mainly employing micro-Raman spectroscopy, micro X-ray tomography (microXCT), Focused ion beam scanning electron microscopy (FIB-SEM), neutron diffraction, X-ray diffraction, small angle X-ray scattering (SAXS), digital volume/image correlation and various (micro-) mechanical testing methods (in situ and/or ex situ) to examine unirradiated and unirradiated fine-grained target graphite materials as well as several other counterparts popular in the nuclear graphite industry. Expecting a comprehensive and sound mechanistic understanding of these representatives of modern fine-grained nuclear graphite could be obtained through this PhD project, validating their reliability in various physical/engineering applications including next generation fission reactor systems (molten salt and HTGRs) and accelerator-driven facilities around the world.